Might as well find a random homeless person defecating on the sidewalk and hand him your deed.

Interest: Rental properties/Fix & Flip (depending on what the numbers say makes the most sense)Goal: Own enough properties to generate $6k/month in order to quit my current job.

If you're a reseller, then these sales do not generate capital gains. 

I also am considering other ways to generate this capital (aside from my day to day work job) and wholesale seems promising.

If you're looking for sense in old plumbing and wiring runs, you're gonna go mad.Often stuff like this comes from many generations of people coming in and doing little repairs without thinking the whole system through, just trying to get something to work in the moment.

Otherwise, when you jump in with all chips on the table, you might find yourself in a bind picking out random contractors that don't know what they are doing while at the same time overcharging you.BiggerPockets has a Rehab Estimator that you should check out.

The stuff sitting on the market is often nice but overpriced, or junk tenants, mediocre location, etc.An owner with a nice product that generates multiple offers in the first week isn't going to typically go to contract with you when the property is not even listed for sale yet or is listed but not under contract.

Think how much more cash you could generate if your real estate investments didn’t use up your time.

Businesses can often generate far better returns than real estate but this sounds a little off.

If I go with a single person but my cleaning needs are random - a Friday here, a Wednesday there, etc. - is that going to be too hard for them to handle?